Blowpipe or cutting torch for flame cutting or removal of metal



1952 L. G. BUCKLE BLOWPIPE OR CUTTING TORCH FOR FLAME CUTTING OR REMOVAL OF METAL 2 SHEETS-SHEET 1 Filed Dec. 2, 1947 m 2 i E g 8 g w a Dec. 23, 1952 1.. G. BUCKLE 2,622,568

BLOWPIPE OR CUTTING TORCH FOR FLAME CUTTING OR REMOVAL OF METAL Filed Dec. 2, 1947 2 Sl'lEETS-SHEET 2 I21) l. 6 Bil/Okla Patented Dec. 23, 1952 BLOWPIPE OR CUTTING TORCH FOR FLAME METAL CUTTING OR REMOVAL OF Leslie George Buckle, Sheffield, England Application December 2, 1947, Serial No. 789,148 In Great Britain December 20, 1946 13 Claims.

This invention relates to an improved blowpipe or flame cutting torch (hereinafter referred to as the cutting torch or the torch) of the type wherein one or more suitable combustible gases (hereinafter referred to as fuel gas) and oxygen (hereinafter with reference to the gaseous mixture referred to as heating oxygen as distinct from the cutting oxygen) are mixed in requisite proportions during their passage through the torch to the torch nozzle to form a combustible gaseous mixture, which issues from the nozzle and, when ignited forms a, jet of flame for the purpose of pre-heating the metal to be cut or removed to a high temperature, known as the kindling point, at which it will burn when a separate flow of oxygen for cutting is caused to issue as a cutting jet from the nozzle through or alongside the pre-heating flame and impinge on the heated metal.

In the common practice of metal cutting by burning, as described above, it is customary that the volume of the gaseous mixture consumed to form the pre-heating flame and therefore the intensity of the pre-heating flame remains constant over both the pre-heating period and the period of the actual cutting or burning operation.

Further during the pre-heating period, it is necessary to utilise a considerable volume of the gaseous mixture in order to bring the metal rapidly to its kindling point; however, when the oxygen jet is caused to impinge on the preheated metal and actual combustion of the metal is initiated and supported, a, secondary source of heat is created, which pre-heats the metal in advance of the oxygen jet more rapidly than the pre-heating jet flame and consequently, while the combustion of the metal is sustained, the volume of the pre-heating flame is greater than is required for this stage of the operation.

It will be seen, therefore, that while the preheating flame is maintained at constant intensity during both the pre-heating and the cutting stages, the gaseous mixture consumed during the cutting stage is far in excess of the actual requirement and therefore this method is wasteful, uneconomical and costly.

It has been previously proposed to take advantage of the secondary source of heat, referred to above, for maintaining the metal to be burnt at its kindling point, by automatically reducing the volume of the gaseous mixture supplied to the nozzle during the pre-heating stage as soon as the cutting oxygen is caused to impinge on, and initiate the combustion of, the metal itself, or by providing a small constant volume flame at the pre-heating jet and, on cessation of actual cutting, converting the gaseous flow from the cutting jet from a normal supply of cutting oxygen to a supply of gaseous mixture, whereby the two jets together provide an augmented pre-heating flame.

Previously proposed cutting torches operating according to the above described principles are subject to a great drawback in that they do not properly retain the correct gaseous balance to provide a neutral or non-oxidising flame under changing conditions of oxygen pressure; this disadvantage is particularly noticeable Where reduction of the pre-heating flame is produced by partial closure of the heating gas passage after mixing.

It is, therefore, the specific object of this invention to provide a cutting torch having improved control means whereby the consumption of the gaseous mixture during the cutting stage is reduced with consequent saving of operating costs, but without prejudice to the cutting efficiency of the torch and such that the neutral or non-oxidising balance of the flame at the preheating jet is maintained at all times during operation of the torch.

The invention consists in a cutting torch of the type indicated wherein an uncontrollable constant flow of balanced gaseous mixture is supplied at all times to the pre-heating jet, sufficient to ensure a permanent and proper source of heat for the cutting period and wherein a supplementary flow of balanced gaseous mixture is automatically supplied to the pre-heating jet for pre-heating periods to augment the constant flow whenever the said cutting period is discontinued.

It is a further object of the invention to provide a cutting torch of the type described having a definite and constant consumption of fuel gas and oxygen per unit time of operaion, which cannot be influenced or altered by an inexperienced or careles operator.

In the accompanying drawings:

Figure 1 shows diagrammatically the layout of the supply lines and valves for the oxygen and the fuel gas of a flame cutting torch according to the invention,

Figure 2 is a part sectional side elevation of a flame cutting torch constructed according to the invention,

Figure 3 is a front elevation of the valve block shown in Figure 2,

Figure 4 is a rear elevation of the valve block shown in Figures 2 and 3,

Figure 5 is a diagram of the supply passages and valves provided in the valve block of a flame cutting torch according to the invention,

Figure 6 is a ghost isometric view of the valve block shown in Figures 2, 3 and 4, viewed from the rear, showing the valves and valve operating mechanisms in exploded relationship to the block,

Figure '7 is a partial section of the valve block alone on the line l---'! of Figure 4, shown without valves and valve operating mechanism, and

Figure 8 is a partial section of the valve block alone on the line 88 of Figure 4, shown without valves and valve operating mechanism.

In carrying the invention into effect according to one mode by way of example, in a steel cutting torch, shown diagrammatically in Figure 1, an oxygen supply line I, which can be connected to a conventional source of pressurized oxygen (not shown) bifurcates into two main branches, a heating oxygen branch 2 and a cutting oxygen branch 3. The heating oxygen branch 2 bifurcates again into two subsidiary branches, a heating oxygen constant supply branch 4 and a heating oxygen supplementary supply branch 5. The cutting oxygen branch 3 is controlled by a cutting oxygen valve 6, to be described hereafter, which opens or closes to supply cutting oxygen to the pipe 2| and thence to the oxygen jet 1 of the nozzle 8 of the cutting torch. The heating oxygen branch 2 is provided with an adjustable heating oxygen valve 9, which is adjusted before the pre-heating operation starts to regulate the supply of heating oxygen for mixing with the fuel gas to the proportion suitable for the type of fuel gas used to produce the highest temperature neutral pre-heating flame. The heating oxygen valve 9 controls the flow of oxygen to both of the heating oxygen branches 4 and 5. The

heating oxygen constant supply branch 4 is uncontrolled, that is to say no valve or other means, which can be adjusted during cutting operations (i. e. While gases are flowing in the torch) are imposed in the branch, which connects with a heating oxygen injector tube 22 terminating in a small bore injector nozzle I!) which discharges into a Venturi mouth ll of a mixing chamber i2, referred to further hereafter. The heating oxygen supplementary supply branch 5, however, is controlled by a heating oxygen supplementary supply valve I3, which, in a manner to be described hereafter, opens or closes to supply or cut off a supplementary flow of heating oxygen to the heating oxygen constant supply branch 4 with which the supplementary branch reconnects after the valve I 3. Thus, the quantity of heating oxygen delivered by the injector nozzle H], can be augmented or reduced by respectively opening or closing the valve [3.

A combustible gas supply line M, which can be connected to a conventional source of a suitable pressurised combustible gas (hereafter referred to as fuel gas), which forms with the heating oxygen the gaseous heating mixture for the preheating flame, bifurcates into two branches, the fuel gas constant supply branch l5 and a fuel gas supplementary supply branch 16-. The constant supply branch I5 is uncontrolled similarly to the heating oxygen constant supply branch 4, previously described, and delivers a supply of fuel gas to the Venturi mouth ll of the mixing chamber l2 through an annular conduit IT, in which the heating oxygen injector nozzle I0 is coaxially located, whereby the discharge of compressed oxygen through the injector nozzle l0 assists in drawing the fuel gas from the conduit ll into the mixing chamber. The mixing chamber I2 is connected with an annular pre-heating jet is located around the cutting jet l in wellknown manner. The fuel gas supply line I4 is provided with control means, for example a valve or cock I 9, to open or close the supply of fuel gas to the torch. The fuel gas supplementary supply branch 26 is controlled by a fuel gas supplementary supply valve 3.0 which, in a manner to be described hereafter, opens 01- closes to supply or cut off a supplementary flow of fuel gas to the fuel gas constant supply branch 5 with which it re-connects after the valve 20. Thus, the quantity of fuel gas delivered to the annular conduit l! and thence to the mixing chamber [2, can be augmented or reduced by respectively opening or closing the valve 20.

In this manner the oxygen supply is divided into three branches:

(a) The cutting oxygen branch 3, controlled by valve 6 and connected to the cutting jet 1 of the torch,

(b) The heating oxygen constant supply branch l, having no control valves or other similar means and connected to the injector tube 22 to deliver heating oxygen to the mixing chamber i2, and

(c) The heating oxygen supplementary supply branch 5, controlled by valve l3 and connected to the heating oxygen constant supply branch l to augment or reduce the supply of heating oxygen delivered to the mixing chamber l2 through the injector tube 22,

and the fuel gas supply is divided into two branches:

(cl) The fuel gas constant supply branch [5, having no control valves or other similar means and connected to the annular conduit I l to deliver fuel gas to the mixing chamber l2, and

(e) The fuel gas supplementary supply branch l6, controlled by valve 26 and connected to the fuel gas constant supply branch 15 to augment or reduce the supply of fuel gas delivered to the mixing chamber I2 through the annular conduit ll.

In order to provide the necessary control of the cutting oxygen supply and the gaseous heating mixture, produced by the mixing of the heating oxygen and the fuel gas in the mixing chamber I2, the control valves 6, l3 and 20 are arranged to be operable in a timed relationship to one another, such that when valve 6 in the cutting oxygen branch 3 is opened, valve H3 in the heating oxygen supplementary supply branch 5 and valve 29 in the fuel gas supplementary supply branch [6 simultaneously close and that when valve 6 is closed, valves l3 and 29 simultaneously open.

The control thus imposed influences the supply of oxygen and fuel gas to the torch nozzle as follows:

(a) When the cutting oxygen valve 6 is closed, heating oxygen and fuel gas are supplied to the mixing chamber l2, and thence to the annular pre-heating jet l8, through both the constant and supplementary supply branches of the oxygen and the fuel gas lines, since valves I3 and 29 are open. In this manner the only gaseous supply to the torch nozzle 8 is a gaseous mixture produced in the mixing chamber from the combined supply of the constant and supplementary branches of the heating oxygen and the fuel gas lines.

(b) When the cutting oxygen valve 6 is opened, cutting oxygen is supplied through the pipe 2| to the cutting jet 1 of the torch nozzle, and, since both valves l3 and 20 are simultaneously closed, the volume of the gaseous heating mixture available to the mixing chamber I2, and hence to the annular pre-heating jet 5%, is reduced to be only that supplied by the constant supply branches of the heating oxygen and the fuel gas lines. In this manner the gaseous supply to the torch nozzle 8 comprises that of the cutting oxygen to the cutting jet 1 and that of the reduced volume of the gaseous heating mixture produced in the mixing chamber from the constant supply branches only of the heating oxygen and the fuel gas lines.

The heating oxygen and fuel gas supply and control are, however, preferably to be considered as providing a pre-heating flame, which, during cutting, that is when cutting oxygen valve 6 is open, has the minimum intensity and volume compatible with efficient cutting and which, during pre-heating, on the closing of the cutting oxygen valve 6, is augmented to a normal intensity and volume pre-heating flame by the additional volume of gaseous mixture supplied by the supplementary branches on the opening of the valves 13 and 29 in the manner previously described.

To enable the constant supply branches to deliver a correctly balanced and correctly metered supply of gaseous mixture to produce this minimum pre-heating flame, the constant branches of both the heating oxygen and the fuel gas lines are provided with accurately pre-determined and balanced restrictions, 23 and 25, respectively, which are pre-set permanently and unalterably for the particular fuel gas for which the torch is used. A detailed description of the form and construction which these restrictives may take is included hereafter.

The valves and supply branches which connect with the cutting oxygen pipe 2!, the injector tube 22, and the annular conduit i! and also with the main oxygen supply line I and the main fuel gas supply line it may be incorporated within a single valve or control block 25 indicated diagrammatically in Figure 1 by the area bounded by the broken line.

Referring now'to Figures 2, 3 and 4, the cutting torch illustrated is a mechanical embodiment of the torch shown diagrammatically in Figure 1 and comprises fundamentally a handle 26 on which the valve block 25 is firmly mounted and which encloses the oxygen and fuel gas supply lines I and I4, connected to the valve block, and a torch head 2?, which is connected to the valve block 25 by the cutting oxygen pipe 21 and by the pre-heating gases delivery line comprising the mixing chamber l2 and a tube 23 which surrounds the injector tube 22 and which is secured at one end to the mixing chamber l2 and at the other to a connecting member 29 mounted in the valve block 25 in a manner to be later described. The torch head Z'l carries the nozzle 3 which forms with the cutting oxygen jet l the annular pre-heating jet l8.

Within the tube 28 and coaxial therewith is located the heating oxygen injector tube 22 in spaced relationship to provide the annular conduitll for the fuel gas supply. The small bore injection nozzle It is secured to the end of the injector tube 22 as by threads Illa and is located in spaced proximity to the Venturi mouth ll of the mixing chamber E2, the arrangement being such that the discharge of the relatively high pressure oxygen through the injector nozzle I B assists in drawing the lower pressure fuel gas from the annular conduit ll through the Venturi mouth H and into the mixing chamber t2, the injector nozzle I ll being provided with a plurality of spaced peripherally disposed axially aligned grooves Hlb connecting the annular conduit ll with a clearance space between the tip of the injector nozzle Ill and the inclined rear wall Ila of the Venturi mouth i l. The arrangement of the injector nozzle Hi and Venturi mouth It further constitute an anti-flashback device in known manner.

The external controls on the valve block 25 (see also Figure 6) comprise a control knob 91) for manipulation of the heating oxygen valve 9 by which the preliminary adjustment of the preheating fiame previously described is obtained and a butterfly type control lever 611 for controlling the valves 6, I3 and 20 (see Figures 1, 5 and 6) in the manner previously described. Rotation of the control knob 9b causes a valve member 9a to advance to close, or withdraw to open, the heating oxygen valve 9, by means of the interengagement of suitable slow threads 9d on the valve member 9a and a bushing provided around the valve member 941 for mounting and sealing the valve assembly into the valve block 25. The butterfly control lever 601 is secured to the rearward end of a valve member 6a, the rotation of which opens or closes the oxygen cutting valve 6 and simultaneously oppositely closes or opens the heating oxygen supplementary supply valve l3 and the fuel gas supplementary supply valve 28 by means of a one-to-one gear linkage from a gear Eb, secured to the end of the valve member 6a of the cutting oxygen valve 6 remote from the control lever 6d, to a gear 131) secured to a valve member l3a of the heating oxygen supplementary supply valve i3 and to a gear 20b secured to a valve member 20a of the fuel gas supplementary supply valve 26. The gears 6b, 13b and 2617 may be provided with a suitable shield or shrouding (not shown) against clogging or damage. The valve members 6a, [3a and 2ila are secured to the valve block against displacement and gas leakage by suitably packed threaded bushings, 60 at each end of members 6a and I30 and 20c at the projecting ends of members l3a and 20a respectively.

The valve block 25 may conveniently be of hexagonal cross section as shown in Figures 2, 3, 4 and 6 so that during manufacture of the block inclined bores may be started on the facets of the hexagon enabling drilling to proceed substantially normal to a face; any other suitable shape or section can be used, however, to contain all or part of the valves and supply branches providing the oxygen and fuel gas supply and control according to the invention.

In Figures 5 and 6 the effective arrangement of valves and supply branches in the valve block is the same and in the following description of such arrangement reference can be made to either figure; the directions of gaseous flow, however, being shown only on Figure 5.

The oxygen supply line I is secured within a recess la provided in the rear face of the valve block 25 by a suitable gas-tight joint (not shown) .A bore lb communicates with the opening Ia and bifurcates' into the heating oxygen supply branch 2 and a branch 3a forming the first section of the cutting oxygen supply 3' (see Figure 1).

Tracing firstly the heating oxygen supply, the branch 2 enters the heating oxygen valve 9, the valve member 9a of which controls the flow of oxygen from the branch 2 to the two subsidiary branches of th heating oxygen supply, the constant supply branch section to and the supplementary supply branch 5a. The constant supply branch section 4a includes the restriction 23, having the function previously described, shown in Figure 6 as being formed by a reduced diameter bore connecting the branch section la with the valve 9. A section section ib of the constant supply connects the first section do with a recess 4d formed in the front face of the valve block to accommodate and secure the end of the heating oxygen injector tube 22 (see also Figure 2). Thus when the valve 9 is opened, preparatory to the commencement of work, the heating oxygen constant supply flows from the heating orygen supply branch 2 through valve 53, through the restriction bore 23 into the bore 4a and thence through here 6b into the injector tube 22 secured in the recess 4d. The bore of the supplementary supply branch 5a for the heating oxygen leads from the valve 6 to the valve i3, which when in the open position has a transverse port Hit in the valve member Illa aligned with the bore 5a and a continuation thereof 51? to allow a supplementary flow of heating oxygen to pass through the bore 5?) which connects with the bore 4a of the heating oxygen constant supply branch l, whereby the volume of the constant supply of heating oxygen delivered to the injector tube 22 is augmented.

The second branch 3a of the bore lb connects the oxygen supply to the cutting oxygen valve 5, the valve member Ea of which is provided with a connecting port 3b adapted to connect the bore of the branch 3a with a bore which completes the connection of the cutting oxygen supply 3 with the cutting oxygen supply pipe 2! located and secured in a recess 3d provided centrally on the front face of the valve block.

The fuel gas supply line It is secured within a recess I401. provided in the rear face of the valve block 25 by a suitable gas-tight joint (not shown) and to this recess I4a are connected the two branches of the fuel gas supply, the constant supply branch 55 and the supplementary supply branch first section Isa. The bore I5 of the constant supply branch is connected to the recess Ida by the restriction 24, having th function previously described, shown in Figure 6 as being formed by a reduced diameter bore. At its other end the bore l5 enters the side wall of a recess I: provided on the front face of the valve block 25 coaxially with, but of greater diameter than, the recess 4d. In this recess [5a the connecting member 29 previously referred to is accommodated and secured to provide mounting for the tube 28, the member 29 being apertured in register with the orifice of the bore IE to connect the bore I5 with the annular space between the inner surface of the member 29 and the outer surface of the injector tube 22, which space communicates with the annular conduit H. The first section I6a of the supplementary supply branch extends from the recess Ida to the fuel gas supplementary supply valve 29, the valve member 20a of which is provided with a transverse port 20d. On rotation of the valve member 20a the port 2011 is brought into register with the bore of the first section I6a and with a continuation bore- I 62; which completes the supplementary supply branch by re-connecting it with the constant supply branch I5 beyond the restrictive 24, whereby on opening the valve 20, a supplementary flow of fuel gas is passed through the bore IBa, the'port 20d and the bore I6b to augment the flow of fuel gas passing through the constant supply branch I5 to the annular conduit IT.

The ports I3d and 20d of the valve members l3a and 20a are adapted, as in respect of the diameters thereof for example, to control and balance the gas flow therethrough to proportion the said flows similarly to the balance restrictives 23 and 24 in the constant flow bores.

The restrictives 23 and 24 may take the form of short bores of accurately predetermined diameter drilled through the material of the valve block itself, as shown in Figure 6, but the invention is not in any way limited to this construction of the restrictives. For example, threaded jets 23 and 24' (see Figures 7 and 8) may be screwed into bores i and I5 which are bores lu and I5 modified by threading and keeping the bores open to the block surface. The open ends of the bores are closed by suitable removable means, as by the screw plugs Bil and 3 I. The threaded jets 23 and 24' have accurately predetermined bores and impose restriction of, and balance between, the constant supply flows of heating oxygen and fuel gas. In this manner, a plurality of threaded jets having differently pre-determined bores may be provided with each torch, so that each torch can be pre-adjusted to suit the characteristics of the particular fuel gas used, e. g. acetylene, hydrogen, propane or other suitable fuel gas used in the art.

The operation of the torch described above, having previously adjusted or permanently set balanced restrictions, is as follows:

(a) With valves 9 and 6 and the cock I9 closed the torch is connected to the sources of oxygen and fuel gas which are adjusted to suitable operating pressures.

(b) Valve 9 and the cock I9 are opened and the gaseous heating mixture issuing from the nozzle 8 ignited in the normal manner.

(0) Valve 9 is then further adjusted until a suitable pre-heating flame (i. e. the neutral flame) is obtained.

The torch is now ready for pre-heating the metal to be cut or removed. When the metal on which the pre-heating flame is being played reaches kindling point the valve 5 is opened by rotating the butterfly lever 6d, whereupon a jet of oxygen impinges on the heated metal causing it to burn, the pre-heating flame, however, being automatically reduced in size and intensity to that fed only by the volume of gaseous mixture supplied by the constant supply branches 4 and I5 of the heating oxygen and the fuel gas respectively.

To reinstate pre-heating the butterfly control lever is returned to its original position causing valve 6 to close and valves I3 and 20 to open to augment the constant supply of gaseous mixture and provide a normal pre-heating flame of full volume and intensity.

In the foregoing description, the means for carrying out the control of the gaseous mixture with respect to the cutting oxygen according to the invention have been described by way of example only and are in no way limiting to the scope of the invention. Thus, the means for ensuring simultaneous operation of the cutting oxygen valve and the supplementary flow valves may take the form of mechanism responsive to the pressure of the flowing cutting oxygen or a combination of such pressure responsive mechanism and toothed gear linkage described or other suitable equivalent means.

In connection with the provision of the threaded jet restrictives previously described, the torch may be provided with a plurality of selectively insertable supplementary bore Valve memhers having valve ports of different pro-determined diameters, whereby the proportions of the supplementary flows of the heating oxygen and fuel gas can be varied to provide the requisite balanced gaseous mixture according to the characteristics of the fuel gas to be used.

I claim:

1. A cutting torch of the type indicated comprising separate oxygen and fuel gas main supply lines, a nozzle having cutting and preheating jets, a chamber connected to said reheating jet for mixing oxygen and fuel gas to provide a gaseous mixture, a pair of unvaled conduits connecting the chamber with the oxygen and fuel gas main supply lines respectively, each unvalved conduit having at least a portion of such minimum cross-sectional area as to meter the flow of gas through the conduit, a pair of supplementary conduits connected one to each of said unvalved conduits and to the respective main supply line, a valve in each of said supplementary conduits, a cutting oxygen supply conduit connecting said oxygen main supply line with the cutting jet in said nozzle, a valve in said cutting oxygen conduit, and valve control means interconnecting said cutting oxygen valve and said supplementary conduit valves and operable to open said cutting oxygen valve while closing said supplementary conduit valves and to close said cutting oxygen valve while opening said supplementary conduit valves, the arrangement being such that metered constant flows of heating oxygen and fuel gas are supplied at all times through the unvalved conduits therefor and mixed in the torch prior to issuance from the preheating jet of the nozzle to ensure a permanent and proper source of heat for the cutting period and that supplementary flows of heating oxygen and fuel gas will augment said constant flows automatically Whenever the cutting oxygen supply to the nozzle is shut off, providing thereby an increased flow of gaseou mixture at the reheating jet for preheating purposes.

2. A cutting torch of the type indicated comprising separate oxygen and fuel gas main supply lines, a nozzle having cutting and preheating jets, a chamber connected to said preheating jet for mixing oxygen and fuel gas to provide a gaseous mixture, a pair of unvalved conduits each having a flow metering restriction therein and connecting the chamber with the oxygen and fuel gas main supply lines respectively, a pair of supplementary conduits connected one to each of said unvalved conduits and to the respective main supply line to by-pass said restriction, a valve in each of said supplementary conduits, a cutting oxygen supply conduit connecting said oxygen main supply line with the cutting jet in said nozzle, a valve in said cutting oxygen conduit, and valve control means interconnecting said cutting oxygen valve and said supplementary conduit valves and operable to open said cutting oxygen valve while closing said supplementary conduit valves and to close said cutting oxygen valve while opening said supplementary conduit valves, the arrangement being such that constant flows of heating oxygen and fuel gas are supplied at all times through the unvalved conduits therefor in proportions balanced by said restrictions and mixed in the torch prior to issuance from the preheating jet of the nozzle to ensure a permanent and proper source of heat for the cutting period and that supplementary flows of heating oxygen and fuel gas will augment said constant flows automatically whenever the cutting oxygen supply to the nozzle is shut off, providing thereby an increased flow of gaseous mixture at the preheating jet for preheating purposes.

3. A cutting torch as claimed in claim 2, wherein each restriction comprises a bore of predetermined diameter. j

4. A cutting torch as claimed in claim 3, wherein each restriction comprises a jet removably insertable into its associated unvalved conduit while the torch is inoperative.

5. A cutting torch as claimed in claim 1, wherein the combined valve control means provides simultaneous displacement of the cutting oxygen valve and the supplementary conduit valves.

6. A cutting torch as claimed in claim 1, wherein said supplementary conduits, the valves therein, the cutting oxygen valve and the combined valve control means are mounted in a single block.

7. A cutting torch as claimed in claim 2, wherein said supplementary conduits, the valves and restrictions therein, the cutting oxygen valve and the combined valve control means are mounted in a single block.

8. A cutting torch as claimed in claim 1, wherein the oxygen main supply line is provided with an adjustable valve whereby the proportions of the gaseous mixture can be adjusted to provide a suitable non-oxidising preheating flame prior to the commencement of work.

9. A cutting torch as claimed in claim 8, wherein said adjustable valve is located in the oxygen main supply line at the junction of the oxygen main supply line and its associated un valved constant flow conduit.

10. A cutting torch as claimed in claim 2, wherein the oxygen main supply line is provided with an adjustable valve whereby the proportions of the gaseous mixture can be adjusted to provide a suitable non-oxidising preheating flame prior to the commencement of work.

11. A cutting torch as claimed in claim 10, wherein said adjustable valve is located in the oxygen main supply line at the junction of the oxygen main supply line and its associated unvalved constant flow conduit.

12. A cutting torch of the type indicated comprising separate oxygen and fuel gas main supply lines, a nozzle having cutting and preheating jets, a chamber connected to said preheating jet for mixing oxygen and fuel gas to provide a gaseous mixture, a pair of unvalved conduits connecting the chamber with the oxygen and fuel gas main supply lines respectively, a pair of supplementary conduits connected one to each of said main supply lines and in communication with said mixing chamber, a valve in each of said supplementary conduits, a cutting oxygen supply conduit connecting said oxygen main supply line with the cutting jet in said nozzle, a valve in said cutting oxygen conduit, and valve control means interconnecting said cutting oxygen valve and said supplementary conduit valves and 11 12 operable to open said cutting oxygen valve While a flow metering restriction therein by-passed by closing said supplementary conduit valves and the associated supplementary conduits. to close said cutting oxygen valve While opening LESLIE GEORGE BUCKLE.

said supplementary conduit valves, the arrangement being such that constant flows of heating FERENCES CITED oxygen and fuel gas are supplied at all times The following references are of record in the through the unvalved conduits therefor and fil of this patent;

mixed in the torch prior to issuance from the preheating jet of the nozzle to ensure a perma- UNITED STATES PATENTS nent and proper source of heat for the cutting 10 Number Name Date period and that supplementary flow of heating 1,201,378 Stet'tner Oct. 17, 1916 oxygen and fuel gas will augment said constant 1,233,423 Wallace July 17, 1917 flows automatically Whenever the cutting oxygen 1,494,747 Jenkins May 20, 1924 supply to the nozzle is cut off, providing thereby 1,537,481 McCutcheon May 12, 1925 an increasedfiow of gaseous mixture at the pre- 15 1,721,569 McCutcheon July 23, 1929 heating jetfor preheating purposes. 1,771,511 Quelch July 29, .1930 13. A cutting torch as claimed in claim 12, 2,190,356 Fausek et a1 Feb. 13, 1940 wherein each of the unvalved conduits includes 2,482,843 Crouch Sept. 27. 1949 

